1. Field of the Invention
This invention discloses the application of new apparatus to enable improving the operation of an internal combustion engine system by selectably controlling the temperature of the cooling water in the engine.
Conventional practice in achieving water cooling for internal combustion engines is to arrange an external radiator with supply and return connections and hoses for appropriate connection to the engine, the cooling water medium being circulated through the engine to the external radiator and back by means of a water pump. It is typical in such cooling systems that a thermostatic flow control valve be provided in the water flow path to enable the engine to achieve normal operating temperature quickly, but also to maintain a substantially steady state temperature according to a pre-arranged temperature set point setting, regardless of variable conditions imposed on the engine. Typically, thermostat settings used in internal combustion engine applications are chosen in the range of 160 deg. F. to 195 deg. F. Such thermostats typically have a non-adjustable set-point and the thermostats are only removed and replaced infrequently in response to failure. In such cases they are typically replaced by a thermostat of a similar set-point temperature in accordance with the original manufacturer's specifications.
It has been known for individual automobile and light truck operators to substitute thermostats of different temperature set points for summer versus winter operation, believing that there will be less risk of engine and transmission overheating if, for example a 160 deg. F. thermostat is used in summer, but that the interior heater will be more effective if a higher temperature thermostat, for example 195 deg. F., is substituted for winter use. The inventor also notes that the radiator cooling system performs at least the auxilliary function of cooling the oil of a vehicle's automatic transmission and that it would similarly benefit from the seasonal changing of low and high temperature thermostats. This seasonal changeover is problematic, however, in that it requires considerable manual effort for removal and exchanging the summer and winter thermostats to accommodate the changing of the seasons.
The inventor has observed that light vehicles manufactured in North America may be equipped from the factory with a higher thermostat set-point of, for example, 195 deg. F., whereas light vehicles from Japan may be equipped from the factory with a lower thermostat set-point of, for example, 160 deg. F. This inventor has observed, however, that vehicles provided with the higher temperature set-point may suffer from poor performance in summer, and those provided with the lower thermostat set point may suffer from poor interior heater output under, for example, winter conditions.
The practical difficulty of changing an engine's water temperature set-point in response to or in anticipation of any particular operating condition or environment imposed upon or anticipated for the engine may also be seen as an impediment to vehicle manufacturers in seeking to fully optimize the operating conditions of the internal combustion engine. It is known by performance enthusiasts, for example, that torque and power output of an engine can be maximized by running the engine under "cooler" water temperature conditions. Also, at least some researchers have recognized that engine knocking is affected by the temperature of the engine's cooling water. It is therefore clear that efforts to optimize this engine operating condition have been hampered by the lack of a simple and practical method of providing a selectable set-point for the internal water temperature condition of the internal combustion engine.
For these reasons a primary objective of this invention is to provide apparatus enabling the selection of one or the other of a higher or lower temperature setpoint from, for example, a relatively "high" set point temperature of 195 deg. F. to a relatively "low" 160 deg. F. in a typical automotive internal combustion engine, without substantial manual effort or disassembly of components of the engine system. Another objective is to provide suitable apparatus to enable a simple retrofitting of existing vehicles with enabling apparatus. Other objectives are to construct such apparatus as utilizing ordinary, inexpensive and readily available thermostatic control valve elements and to avoid complex or costly or bulky additional componentry to be added to the engine system.
2. Description of the Related Art
One avenue of providing apparatus capable of varying the water temperature set-point in an internal combustion engine was disclosed in U.S. Pat. No. 5,390,632 by Ikebe et al. in which were arranged multiple temperature and air pressure sensors, engine speed sensor and a knocking detector in a system to provide inputs to a computer; the computer being programmed to make certain decisions in response to the inputs, such decisions resulting in, for example, the variable operation of a water flow control valve, a cooling fan and a variable speed water pump. This system is obviously complex, expensive, subject to maintenance attention and unsuitable for retrofit application to vehicles already in service. Other novel cooling system apparatus described in known prior art is similarly more complex and less practical to apply to new or existing internal combustion engines than the present invention.